This study evaluates three models for pesticide runoff at field-edge: Pesticide Root Zone Model (PRZM), Root Zone Water Quality Model (RZWQM) and OPUS. We compare their methods for representing key hydrological and pesticide processes. We further evaluate the models using measurements from three field studies conducted at the Central Valley of California with flood and sprinkler irrigation.  Sensitivity analysis is conducted to identify important parameters. Theoretical evaluations indicate that RZWQM and OPUS meet the following requirements:  simulate flood irrigation, subsurface flow via macropores, management practices, mechanistic approaches for hydrology simulation and fine timestep; while PRZM does not. RZWQM and OPUS have also more advanced components for pesticide sorption accounting for non-equilibrium status and nonlinear adsorption.  Simulations of the field studies indicate that for sprinkler irrigation, all models simulate pesticide runoff with good accuracy (mean absolution percent error: 0.4-161%). For flood irrigation, PRZM does not perform as well as RZWQM and OPUS. The five pesticides studied are hydrophilic; simulation of sediment erosion and hydrophobic pesticides remains challenging. RZWQM lacks sediment erosion component; OPUS and PRZM generate results with large errors.  In conclusion, OPUS and RZWQM appears desirable; yet, both models need improvements on sediment erosion.

Modeling pesticide runoff from edge of agricultural fields in California: Evaluation of PRZM, RZWQM, and OPUS models

248th National Meeting (2014)

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